Software-defined networking (SDN) is an approach to computer networking that allows network administrators to manage network services through abstraction of lower-level functionality. This is done by decoupling the system that makes decisions about where traffic is sent (the control plane) from the underlying systems that forward traffic to the selected destination (the data plane).
A security device or appliance, such as, e.g., an intrusion detection system (IDS), is a device or software application that monitors network or system activities for malicious activities or policy violations and produces reports to a management station. IDSs come in a variety of “flavors” and approach the goal of detecting suspicious traffic in different ways. Some systems may attempt to stop an intrusion attempt but this is neither required nor expected of a monitoring system. Thus, IDSs are primarily focused on identifying possible incidents, logging information about them, and reporting and/or notification functionalities.